1. Technical Field
The present invention relates to a communication technology. More particularly, the present invention relates to a communication system having a common ground mechanism.
2. Description of Related Art
A digital communication system brings convenience to people's daily life, in which the digital communication system can convert a user's analog voice signal and/or image to a digital signal for transmission to perform communication. When a multi-user videoconference is performed, signals are often transmitted through a network. However, when one of the participants does not have a computer system that can perform the multi-user conference, the conference cannot be held. Accordingly, it is necessary to provide a device that can establish a multi-user conference when at least one of the participants does not have the computer system.